This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Butyrylcholinesterase (BCHE), or serum cholinesterase, is a non-specific cholinesterase found in blood plasma that hydrolyses choline esters. This project entails the search for modifications of BCHE by organophosphorous compounds such as phenyl saligenin phosphate (PSP) and 2-(o-cresyl)-4H-1:3:2-benzodioxaphosphorin-2-oxide (CBDP).